JP2005166811A - Electromagnetic wave shielding film and electromagnetic wave shielding window material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding film in which the problem of bending is eliminated when it is pasted to a function film while ensuring high adhesion and conduction stability when an electrode is led out. <P>SOLUTION: The electromagnetic wave shielding film comprises a transparent substrate film, and a metal thin film provided on one side of the substrate film and subjected to pattern etching. The metal thin film is subjected to pattern etching such that the numerical aperture at a circumferential edge part 1A becomes smaller than that at the central region 1B other than the circumferential edge part. A frame-like part 3C having zero numerical aperture may be formed between the circumferential edge part 3A and the central region 3B. Since the circumferential edge part 1A is also subjected to pattern etching, the problem of bending is eliminated when it is pasted to a function film. The circumferential edge part 1A has a numerical aperture smaller than that at the central region 1B and since pattern etching is carried out to increase the metal surface, high conduction stability is ensured when an electrode is led out and stripping of the metal thin film is reduced because of high adhesive properties. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electromagnetic wave shielding film and an electromagnetic wave shielding window material suitable as a front filter for a plasma display panel (PDP).

  In order to block the leakage electromagnetic wave of the PDP, a PDP filter having a conductive layer and having an electromagnetic wave shielding function is provided on the front surface of the PDP. Conventionally, a conductive mesh material such as a wire mesh is used as the conductive layer of this PDP filter, which is interposed between two transparent substrates such as an acrylic plate and a glass plate, or such a transparent substrate. The PDP filter was configured by being laminated and integrated on one of the plate surfaces. However, the conductive mesh satisfies the electromagnetic wave shielding property and the light transmission property, and also prevents the moire phenomenon (interference fringes caused by the relationship between the PDP dots and the mesh lattice), thereby obtaining good visibility. In recent years, a metal mesh obtained by pattern etching of a metal foil called “etching mesh” has come to be used (Japanese Patent Laid-Open No. 11-74666).

  This etching mesh is formed by laminating a metal foil to a transparent substrate film such as a PET (polyethylene terephthalate) film, and then forming openings in a lattice shape on the metal foil by pattern etching. According to the pattern etching, the metal foil can be etched into a desired pattern shape, so that the wire diameter and interval of the lattice and the degree of freedom of the mesh shape are much larger than those of the conductive mesh. For this reason, it is possible to realize a PDP filter that has both good electromagnetic shielding properties and light transmissivity and does not cause moire phenomenon.

  In addition, for the purpose of further reducing the thickness and weight of PDP filters, such etching meshes are required for PDP filters such as near-infrared absorbing films, antireflection films, and antiglare films without using transparent substrates such as acrylic plates and glass plates. Those that are directly bonded to other functional films are used as PDP filters. In addition, since the etching mesh and the functional film are bonded together with excellent balance of transparency, adhesiveness, and other performance, a heat mainly composed of ethylene-vinyl acetate copolymer (EVA) resin is used. A cross-linking adhesive is preferably used.

By the way, the PDP filter generally has a rectangular shape in plan view, and in the conventional PDP filter, a black frame coating for determining the effective screen size of the display is applied to the peripheral portion. As shown in FIG. 2 (a), the present inventors have used an etching mesh using a copper foil previously blackened by an antiglare treatment as an electromagnetic wave shielding film that can omit the black frame coating. An etching mesh 10 is proposed in which only the central region other than the above is subjected to pattern etching, and the black frame portion 11 at the peripheral portion also serves as a frame for determining the screen size (Japanese Patent Application No. 2003-303152). Thus, if the etching mesh has a peripheral portion as a non-etched region, there is also an effect that stable conductivity for electrode extraction can be obtained at the peripheral portion.
Japanese Patent Laid-Open No. 11-74666 Japanese Patent Application No. 2003-303152

  As shown in FIG. 2 (a), in the etching mesh 10 having the peripheral portion as a non-etched region, when the functional film shrinks or deforms when integrally bonded to another functional film such as an antireflection film, There is a problem that the frame portion 11 at the periphery of the etching mesh integrated with the bent. Such a problem of bending of the etching mesh due to deformation and shrinkage of the functional film is very likely to occur when the functional film and the etching mesh are heat-bonded using the above-mentioned heat-crosslinking adhesive, It may occur not only when bonding by photocrosslinking by ultraviolet irradiation.

  As shown in FIG. 2 (b), there is no such problem if the etching mesh 10A is pattern-etched uniformly as a whole, but such an etching mesh 10A is inferior in the conductive stability for electrode extraction, In addition, since the adhesion area of the pattern-etched metal foil is reduced, there is also a drawback that the metal foil is easily peeled from the transparent base film when the electrode portion comes into contact with the metal ground terminal.

  The present invention solves such problems, there is no problem of bending at the time of bonding with a functional film, and there is also an electromagnetic wave shielding film having good conduction stability and adhesion for electrode drawing, and the electromagnetic wave shield. An object of the present invention is to provide an electromagnetic shielding window material in which a functional film is bonded to a functional film and integrated.

  The electromagnetic wave shielding film of the present invention is an electromagnetic wave shielding film comprising a transparent base film and a pattern-etched metal thin film provided on one surface of the base film. The pattern etching is performed so that the aperture ratio of the peripheral portion is lower than the aperture ratio of the central region other than the peripheral portion.

  The aperture ratio is a percentage of the area ratio of the opening portion in the projected area of the metal thin film.

  In the case of this electromagnetic wave shielding film, since the peripheral portion is also pattern-etched, the problem of bending at the time of bonding with the above-described functional film is solved. In addition, the peripheral portion has a smaller aperture ratio than the central region, that is, the pattern etching is performed so that the metal surface is increased, so that the conduction stability for extracting the electrode is high and the adhesiveness is also good. The problem of peeling of the metal thin film is also reduced.

  In the present invention, a frame-like portion having an opening ratio of zero which is not etched may be formed between the peripheral edge portion and the central region which have been subjected to pattern etching. In this case, this frame-like portion is formed on the PDP. It can be used as a frame for determining the screen size.

  In the present invention, the metal thin film is a metal foil, and is preferably bonded to the base film with a transparent adhesive. Moreover, it is preferable that the aperture ratio of a peripheral part is 70 to 80%, the aperture ratio of a center area | region is 90% or more, and the width | variety of a peripheral part is 3 to 100 mm. Moreover, when providing a frame-shaped part, it is preferable that the width | variety of this frame-shaped part is 5-10 mm.

  The electromagnetic wave shielding film of the present invention has, for example, a substantially rectangular shape, and is pattern-etched so that the opening ratio of the four side edges of the metal thin film is lower than the opening ratio of the central region other than the four edge parts. Can be.

  In the electromagnetic wave shielding film of the present invention, the peripheral portion and the central region are pattern-etched in a lattice shape, and the peripheral portion has a wire diameter larger than that of the central region. The aperture ratio of the peripheral area may be smaller than the aperture ratio of the central area, and the aperture ratio of the peripheral area is made smaller than that of the central area by pattern etching into a pattern shape different from the peripheral area and the central area. May be.

  The electromagnetic shielding window material of the present invention is formed by laminating such an electromagnetic shielding film of the present invention and a functional film, has no problem of bending of the electromagnetic shielding film, and is stable in conduction. Excellent in adhesion and adhesiveness. Examples of the functional film include one or more selected from the group consisting of a near-infrared absorbing film, a color tone correcting film, an antireflection film, an antiglare film, an impact absorbing film, and an antifouling film.

  In particular, the electromagnetic shielding window material uses a heat-shrinkable film that shrinks when heated as a functional film, and the electromagnetic shielding film and the functional film are mainly composed of an ethylene-vinyl acetate copolymer resin. It is effective for an electromagnetic shielding window material bonded with a heat-crosslinking adhesive.

  Embodiments of the electromagnetic wave shielding film and electromagnetic wave shielding window material of the present invention will be described in detail below.

  FIGS. 1A to 1C are plan views showing an embodiment of the electromagnetic wave shielding film of the present invention.

  The electromagnetic wave shielding film of the present invention (hereinafter referred to as “etching mesh”) is different from the conventional etching mesh only in that the aperture ratio by pattern etching is different between the peripheral portion and the central region. The structure of is the same as the conventional one, and a metal foil that has been subjected to pattern etching and anti-glare treatment as necessary is bonded and integrated with a transparent base film such as a PET (polyethylene terephthalate) film by a transparent adhesive. is there. Such an etching mesh is usually manufactured by forming an opening by applying a pattern etching to a base film with a metal foil that has been subjected to an antiglare treatment on one surface, and then applying a pattern etching. . In addition, in this way, when the metal foil with antiglare treatment on one side was bonded to the base film, etc., and after pattern etching, the etched cross section of the metal foil exhibited a metallic luster, depending on the viewing angle Light will be reflected. Therefore, in order to prevent this, in the present invention, after the metal foil is bonded to the base film, pattern etching may be performed, followed by antiglare treatment. Thus, by performing an anti-glare treatment after the etching process, the entire exposed surface of the metal foil including the etched cross section of the opening becomes an anti-glare treatment surface, and reflection of light is prevented.

  Etching mesh transparent substrate film includes PET film, polyester, polybutylene terephthalate, polymethyl methacrylate (PMMA), acrylic plate, polycarbonate (PC), polystyrene, triacetate film, polyvinyl alcohol, polyvinyl chloride, poly Resin films such as vinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyvinyl butyral, metal ion cross-linked ethylene-methacrylic acid copolymer, polyurethane, cellophane, etc. can be used, but preferably PET, PBT (polybutylene). Terephthalate), PC, PMMA, acrylic film, the thickness of which is 1 to 1 to obtain sufficient durability and handleability without excessively increasing the thickness of the resulting etching mesh. Preferably about 00μm.

  Moreover, as metal foil, copper alloy foils, such as Cu-Ni other than copper foil, can be used, The thickness is about 1-200 micrometers normally.

  As a transparent adhesive for bonding the transparent base film and the metal foil, EVA or PVB resin described later can be used as an adhesive resin used for the etching mesh and the functional film of the present invention. Epoxy-based, acrylic-based, urethane-based, polyester-based, and rubber-based transparent adhesives can also be used. In particular, urethane-based and epoxy-based adhesives are particularly desirable from the viewpoint of etching resistance in the etching process after lamination. . The thickness of the adhesive layer made of this transparent adhesive is preferably 1 to 50 μm. The transparent adhesive may contain conductive particles as necessary.

  The method of pattern etching the metal foil may be any method generally used, but photoetching using a resist is preferable. In this case, after a photoresist film is pressure-bonded on the metal foil or coated with a photoresist, pattern exposure is performed using a desired mask, and development processing is performed to form a resist pattern. Thereafter, the portion of the metal foil without the resist may be removed with an etching solution such as ferric chloride solution.

  Moreover, when anti-glare treatment is performed on a metal foil such as copper foil, it is preferable to perform an oxidation treatment with hypochlorous acid from the viewpoint of good contrast.

The etching mesh 1 shown in FIG. 1A has a substantially rectangular shape (however, the etching mesh of the present invention is not limited to a substantially rectangular shape, and may be circular, elliptical, or other polygonal shapes). The metal foil of the etching mesh 1 has openings 1a and 1b formed by lattice-like pattern etching. However, the peripheral frame portion 1A is formed along the peripheral edge, that is, the four side edges. and the line width L _a grid of, is different from the line width L _b of the lattice of the inner central region 1B of the peripheral frame portion, by direction of the line width L _a is thicker than the line width L _b, the peripheral frame part The size of the opening 1a of 1A is smaller than the size of the opening 1b of the central region 1B. As a result, even if the pitches of the lattices are the same in the peripheral frame portion 1A and the central region 1B, the aperture ratio is 1A. Is smaller than the central region 1B.

  Since the entire etching mesh 1 including the peripheral frame portion 1A is subjected to pattern etching, the problem of bending at the time of bonding with the functional film due to the presence of the non-etching region is solved. In addition, the peripheral frame portion 1A has a smaller opening ratio than the central region 1B and is pattern-etched so that the metal surface is increased. Therefore, the conductive stability for leading out the electrode is high, and the metal foil is bonded. And the problem of peeling of the metal foil is reduced.

In such an etching mesh 1, the width W _a of the peripheral frame portion 1 </ b> A that makes the aperture ratio lower than that of the central region 1 </ b> B varies depending on the size of the etching mesh 1, but is usually about 3 to 100 mm. The width W _a is the smaller than the above range, continuity stability by providing the peripheral frame portion 1A of the low aperture ratio, can not be sufficiently obtained effect of improving adhesiveness, the larger, the high aperture ratio The area of the central area 1B becomes small, and the visibility as a PDP filter becomes poor.

  Further, if the opening ratio of the peripheral frame portion 1A is excessively low, it is not possible to sufficiently obtain the bending prevention effect of the present invention by making this portion an etching region. The effect of improving the conduction stability and adhesiveness of the present invention due to the low aperture ratio cannot be obtained sufficiently. Therefore, it is preferable that the opening ratio of the peripheral frame portion 1A having a low opening ratio is 70 to 80%.

  The opening ratio of the central region 1B may be equal to the opening ratio of a normal etching mesh, and is 90% or more, for example, about 90 to 95%.

Therefore, in order to realize such an aperture ratio, for example, as shown in FIG. 1A, when both the peripheral frame portion 1A and the central region 1B are pattern-etched in a lattice pattern, the lattice lines of the peripheral frame portion 1A width _{L a} is 10 to 100 [mu] m, the line width _{L b} of the grating in the central region 1B is preferably about 10 to 30 [mu] m.

  The etching mesh of the present invention only needs to be pattern-etched so that the aperture ratio of the peripheral frame portion 1A is smaller than the aperture ratio of the central region 1B, and the pattern shape of the peripheral frame portion 1A and the central region 1B is sufficient. There are no particular restrictions. For example, in addition to the lattice shape shown in FIG. 1A, a punching metal shape in which openings of a circle, a hexagon, a triangle, an ellipse, or other shapes are formed may be used.

  Further, the peripheral frame portion 1A and the central region 1B are not necessarily limited to those that have been pattern-etched in the same pattern shape at the same pitch, but may have different pitches in the same pattern shape, Pattern etching may be performed in different pattern shapes.

  FIG. 1B shows an etching mesh 2 in which the peripheral frame portion 2A and the central region 2B are pattern-etched in different pattern shapes. The etching mesh 2 is the etching mesh 1 in FIG. 1A. The peripheral frame portion 2A has a punching metal shape in which an elliptical opening is formed.

  In the etching mesh of the present invention, as shown in FIG. 1C, a frame-like portion 3C that is not etched, that is, has an aperture ratio of zero, is formed between the peripheral frame portion 3A and the central region 3B. Etching mesh 3 may be used. The etching mesh 3 has the same configuration as that of the etching mesh 1 in FIG. 1A except that a frame-like portion 3C in a non-etching region is provided between the peripheral frame portion 3A and the central region 3B. By forming the frame-like portion 3C in this way, the frame-like portion 3C can function as a frame for determining the screen size of the PDP.

If thus providing the frame-shaped portion 3C, it is preferable that the width _{W c} of the frame-shaped portion 3C is about 5 to 10 mm. When the width W _c of the frame-shaped portion 3C is smaller than the above range, Eze form a sufficient black frame part as a frame for the screen size determination of PDP, when larger than the above range, the non-etched region is present The above-described problem of bending due to the above occurs.

In the case thus providing the frame-shaped portion 3C, the width W _a of the peripheral frame portion 3A may be slightly smaller than the case without the frame-shaped portion 3C, it is sufficient for example, about 3 to 50 mm, Further, the opening ratio of the peripheral frame portion 3A may be slightly smaller than the case where the frame-shaped portion 3C is not provided, and can be set to, for example, 50 to 80%.

  Needless to say, even in the etching mesh 3 having the frame-shaped portion 3C, the peripheral frame portion 3A and the central region 3B may be pattern-etched in different pattern shapes.

  Such an etching mesh is bonded and integrated with a functional film such as a near-infrared absorbing film, a color tone correcting film, an antireflection film, an antiglare film, an impact absorbing film, an antifouling film, and used as a PDP filter or the like. In particular, the effect of preventing the deflection is effectively exhibited. This is particularly effective when the etching mesh and the functional film are bonded and integrated by heating or ultraviolet irradiation.

  Examples of the adhesive resin used for bonding the etching mesh and the functional film of the present invention include ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene -(Meth) ethyl acrylate copolymer, ethylene- (meth) methyl acrylate copolymer, metal ion crosslinked ethylene- (meth) acrylic acid copolymer, partially saponified ethylene-vinyl acetate copolymer, carboxylated ethylene -Ethylene copolymers such as vinyl acetate copolymer, ethylene- (meth) acrylic-maleic anhydride copolymer, ethylene-vinyl acetate- (meth) acrylate copolymer (in addition, "(meth) “Acrylic” means “acrylic or methacrylic”.) In addition, polyvinyl butyral (PVB) resin, epoxy resin, acrylic resin, phenol resin, silicone resin, polyester resin, urethane resin, etc. can also be used, but the most balanced in terms of performance and easy to use is ethylene-vinyl acetate. It is a copolymer (EVA). In addition, PVB resins used in laminated glass for automobiles are also preferable from the viewpoint of impact resistance, penetration resistance, adhesion, transparency, and the like.

  The etching mesh of the present invention uses a heat- or ultraviolet-crosslinking adhesive mainly composed of EVA, particularly an EVA adhesive film in which a heat-crosslinking adhesive is used as a film, and a film that is easily shrunk by heating as a base film. It is suitable for bonding to a functional film. Examples of the film that is easily shrunk by heating include a PET film, a PE film, and a PP film. The etching mesh of the present invention is particularly bonded to a functional film having such a film as a base film, and a PDP filter. It is effective when manufacturing electromagnetic shielding window materials such as.

  Below, the EVA type adhesive film used for adhesion | attachment with the etching mesh of this invention and a functional film is demonstrated in detail.

  EVA having a vinyl acetate content of 5 to 50% by weight, preferably 15 to 40% by weight is used. If the vinyl acetate content is less than 5% by weight, there are problems in weather resistance and transparency. If the vinyl acetate content exceeds 40% by weight, the mechanical properties are remarkably lowered, and film formation becomes difficult and mutual film blocking occurs. .

  As the cross-linking agent, an organic peroxide is suitable for heat cross-linking and is selected in consideration of sheet processing temperature, cross-linking temperature, storage stability, and the like. Examples of peroxides that can be used include 2,5-dimethylhexane-2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3; -Butyl peroxide; t-butylcumyl peroxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; dicumyl peroxide; α, α'-bis (t-butylperoxyisopropyl) ) Benzene; n-butyl-4,4-bis (t-butylperoxy) valerate; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) cyclohexane; , 1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane; t-butylperoxybenzoate; benzoyl peroxide; Luperoxyacetate; 2,5-dimethyl-2,5-bis (tertiarybutylperoxy) hexyne-3; 1,1-bis (tertiarybutylperoxy) -3,3,5-trimethylcyclohexane; 1-bis (tert-butylperoxy) cyclohexane; methyl ethyl ketone peroxide; 2,5-dimethylhexyl-2,5-bisperoxybenzoate; tert-butyl hydroperoxide; p-menthane hydroperoxide; p-chlorobenzoyl Peroxides; tertiary butyl peroxyisobutyrate; hydroxyheptyl peroxide; chlorhexanone peroxide. These peroxides are used alone or in combination of two or more, and are usually used at a ratio of 5 parts by weight or less, preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of EVA. .

  The organic peroxide is usually kneaded with EVA using an extruder, a roll mill or the like, but may be dissolved in an organic solvent, a plasticizer, a vinyl monomer or the like and added to the EVA film by an impregnation method.

  Various acryloxy group or methacryloxy group and allyl group-containing compounds can be added to improve EVA physical properties (mechanical strength, optical properties, adhesion, weather resistance, whitening resistance, crosslinking speed, etc.). . As the compound used for this purpose, acrylic acid or methacrylic acid derivatives, for example, esters and amides thereof are the most common. As the ester residue, in addition to alkyl groups such as methyl, ethyl, dodecyl, stearyl, lauryl, cyclohexyl groups , Tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, 3-chloro-2-hydroxypropyl group and the like. Further, esters with polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, trimethylolpropane, and pentaerythritol can also be used. A typical amide is diacetone acrylamide.

  More specifically, polyfunctional esters such as acrylic or methacrylic acid esters such as trimethylolpropane, pentaerythritol, glycerin, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate, etc. These are allyl group-containing compounds, and these are used singly or in combination of two or more, usually 0.1 to 2 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of EVA. It is done.

  When EVA is cross-linked by light, a photosensitizer is usually used in an amount of 5 parts by weight or less, preferably 0.1 to 3.0 parts by weight based on 100 parts by weight of EVA instead of the peroxide.

  In this case, usable photosensitizers include, for example, benzoin, benzophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, dibenzyl, 5-nitroacenaphthene, hexachlorocyclopentadiene, p-nitrodiphenyl. , P-nitroaniline, 2,4,6-trinitroaniline, 1,2-benzanthraquinone, 3-methyl-1,3-diaza-1,9-benzanthrone, and the like. Alternatively, two or more types can be mixed and used.

  In this case, a silane coupling agent is used in combination as an adhesion promoter. As this silane coupling agent, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycid Xylpropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- β (aminoethyl) -γ-aminopropyltrimethoxysilane and the like can be mentioned.

  These silane coupling agents are usually used in a mixture of 0.001 to 10 parts by weight, preferably 0.001 to 5 parts by weight, based on 100 parts by weight of EVA.

  In addition, the EVA adhesive film used in the present invention may contain a small amount of an ultraviolet absorber, an infrared absorber, an anti-aging agent, a coating processing aid, a colorant, and the like. Further, a small amount of a filler such as hydrophobic silica and calcium carbonate may be included.

  Further, as means for improving adhesiveness, means such as corona discharge treatment, low temperature plasma treatment, electron beam irradiation, and ultraviolet light irradiation on the sheeted EVA adhesive film surface are also effective.

  The EVA adhesive film used in the present invention is a mixture of EVA and the above-mentioned additives, kneaded with an extruder, roll, etc., and then formed into a predetermined shape by a film forming method such as calendar, roll, T-die extrusion, inflation, etc. Manufactured by sheet molding. During film formation, embossing is applied to prevent blocking and facilitate degassing during pressure bonding with a glass substrate.

  This EVA adhesive film is usually about 50 to 1000 μm in thickness.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

Example 1
The etching mesh 1 of the present invention shown in FIG. 1 (a) is attached to an antireflection film using a PET or TAC film having a thickness of 200 μm as a base film with an EVA adhesive, and the presence or absence of bending and the conductive stability at this time Experiments were conducted to investigate the properties and adhesion.

This etching mesh 1 has a size of 561 mm × 997 mm obtained by pattern etching after adhering a 10 μm thick copper foil to a 125 μm thick PET film. is there.
Width W _a of peripheral frame portion 1A: 3.5 mm
Opening ratio of peripheral frame 1A: 78%
Line width L _a of the lattice of the peripheral frame portion 1A: 35 μm
Opening ratio of central region 1B: 92%
Line width L _b of the lattice in the central region 1B: 12 μm

  This etching mesh 1 is laminated with an antireflection film with an EVA adhesive film interposed therebetween using a 200 μm thick EVA adhesive film so that the copper foil side becomes an adhesive surface, and heated and pressurized at 100 ° C. and 100 kPa. Bonded and integrated under conditions.

At this time, the presence / absence of bending of the etching mesh, conduction stability, and adhesiveness were examined by the following methods, and the results are shown in Table 1.
[Existence of deflection]
The presence or absence of bending was examined by visual observation.
[Conductivity stability]
Examined with a low resistance meter, those having a resistance of 0.12 Ω / cm ² or less were regarded as good continuity stability, and those exceeding 0.12 Ω / cm ² were regarded as poor continuity stability.
[Adhesiveness]
Examined by a JIS Z0238 tensile test, those having 7.0 N / 25 mm or more were considered to have good adhesion, and those having less than 7.0 N / 25 mm were considered to have poor adhesion.

Example 2
Except for using the etching mesh 3 having the frame-like portion 3C shown in FIG. 1C as the etching mesh, the presence or absence of bending when adhered to the antireflection film in the same manner as in Example 1, the conduction stability and The adhesion was examined and the results are shown in Table 1.

The etching mesh 3C used has the same configuration as the etching mesh 1 used in Example 1 except that it has a frame-shaped portion 3C. The dimensions and aperture ratios of the respective portions are as follows.
Width W _a of peripheral frame portion 3A: 3.5 mm
Opening ratio of peripheral frame portion 3A: 78%
Line width of lattice of peripheral frame portion 3A: 35 μm
Opening ratio of central region 3B: 92%
Line width of lattice in central region 3B: 12 μm
The width W _c of the frame-shaped part 3C: 11.5 mm

Comparative Example 1
As an etching mesh, the presence or absence of bending when adhered to the antireflection film in the same manner as in Example 1 except that the etching mesh 10 in which the peripheral frame portion shown in FIG. The conduction stability and adhesiveness were examined, and the results are shown in Table 1.

  The etching mesh 10 used has the same configuration as the etching mesh 1 used in Example 1 except that the peripheral frame portion is a non-etching region, and the size of each part and the aperture ratio of the central region are also implemented. The same as the etching mesh 1 used in Example 1.

Comparative Example 2
As an etching mesh, the presence or absence of bending when bonded to the antireflection film and the continuity in the same manner as in Example 1 except that the etching mesh 10A shown in FIG. The stability and adhesiveness were examined, and the results are shown in Table 1.

  The etching mesh 10A used has the same configuration as the etching mesh 1 used in Example 1 except that the etching mesh 10A used in Example 1 is uniformly etched with the same opening ratio as the central area 1B of the etching mesh used in Example 1. It is said that.

  From Table 1, it can be seen that the etching mesh of the present invention is excellent in conduction stability and adhesiveness, and also has no problem of bending when bonded to a functional film.

  The electromagnetic wave shielding film and electromagnetic wave shielding window material of the present invention are particularly suitable as a PDP filter.

It is a top view which shows embodiment of the electromagnetic wave shielding film of this invention. It is a top view which shows the conventional etching mesh.

Explanation of symbols

1,2,3 Etching mesh (electromagnetic shielding film)
1A, 2A, 3A Peripheral frame portion 1B, 2B, 3B Central region 3C Frame-like portion 1a, 1b Opening

Claims (13)

In an electromagnetic wave shielding film comprising a transparent base film, and a pattern-etched metal thin film provided on one surface of the base film,
The electromagnetic wave shielding film, wherein the metal thin film is subjected to pattern etching so that an opening ratio of a peripheral portion is lower than an opening ratio of a central region other than the peripheral portion.   2. The electromagnetic wave shielding film according to claim 1, wherein the metal thin film has a frame-shaped portion having an aperture ratio of zero between the peripheral edge portion and the central region.   3. The electromagnetic wave shielding film according to claim 1, wherein the metal thin film is a metal foil and is bonded to the base film with a transparent adhesive.   4. The electromagnetic wave shielding film according to claim 1, wherein an opening ratio of the peripheral portion is 70 to 80% and an opening ratio of the central region is 90% or more. 5.   The electromagnetic wave shielding film according to any one of claims 1 to 4, wherein the peripheral edge has a width of 3 to 100 mm.   The electromagnetic wave shielding film according to any one of claims 2 to 5, wherein the width of the frame-shaped portion is 5 to 10 mm.   7. The electromagnetic wave shielding film according to claim 1, wherein the electromagnetic wave shielding film has a substantially rectangular shape, and the metal thin film has an opening ratio of a four-side edge portion of a central region other than the four-edge portion. An electromagnetic wave shielding film, which is patterned to be lower than the above.   8. The peripheral edge portion and the central region according to claim 1, wherein the peripheral edge portion and the central region are pattern-etched in a lattice shape, and the wire diameter of the lattice at the peripheral edge portion is larger than the wire diameter of the lattice in the central region. An electromagnetic wave shielding film characterized by that.   The electromagnetic wave shielding film according to any one of claims 1 to 7, wherein the peripheral edge portion and the central region are subjected to pattern etching in different pattern shapes.   An electromagnetic wave shielding window material comprising the electromagnetic wave shielding film according to any one of claims 1 to 9 and a functional film bonded together.   The electromagnetic shielding window material according to claim 10, wherein the functional film is a heat-shrinkable film that shrinks by heating.   The electromagnetic wave shielding property according to claim 10 or 11, wherein the electromagnetic wave shielding film and the functional film are bonded together by a heat-crosslinking adhesive mainly comprising an ethylene-vinyl acetate copolymer resin. Window material.   The functional film according to any one of claims 10 to 12, wherein the functional film is selected from the group consisting of a near-infrared absorbing film, a color tone correcting film, an antireflection film, an antiglare film, an impact absorbing film, and an antifouling film. An electromagnetic shielding window material characterized by being more than a seed.

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